Question, will your son be a pitcher only?
JMO but the coach should be helping your son to develop a routine, unless he has no clue what a 14 year old should be doing.
Keep it simple. You dont want to burn out before he pitches.
Run poles until he breaks into a sweat, this tells you are warmed up. With rest of team, throwing warm ups with partner. Bullpen to practice pitches. Set on a specific number amount depending on how many pitches he has. At his age he only needs 2-3 pitches. His fastball the #1 pitch. Don't forget to stretch. If he is not a pitcher and hits, he can take batting practice.
Again, keep it simple. He is 14.